Realization · Four Śrāmaṇa FruitionsPart 3Paper 5 of 9

Thinning as Severance

SRAMANA-P05 · v1.0 · 2026-06

Why the Once-Returner Is a Quantum of Reduction, Not a Halfway House

中文主題：薄之為斷——一來果何以是減量而非半途

I. The Question

The subtraction of the first four papers has the skeleton "wholly severed": a fetter severed and abiding, the wall permanently down. The stream-enterer severs the first three fetters — what is severed is wholly severed, what abides wholly abides, clean and clear. But with the second fruit (the once-returner, sakadāgāmin) this cleanness meets trouble. Its mark is not "severs a fetter" but "thinning greed-hatred-delusion" — sensual greed and ill-will are not exhausted, merely attenuated.

This single word "thinning" steps squarely onto the line the first three papers repeatedly drew. From P01 on, this axis has rebutted "measuring fruit by experience" and "measuring progress by degree" as illusions of accumulation; and "thinning" sounds exactly like a degree-magnitude — greed and hatred "grown a little fainter," "lightened a shade." If a fruit can be fixed by "how much fainter," does that not demolish the master-thesis of subtraction held through four papers? On what ground does a wall taken down only halfway count as a "fruit"? This is the first real difficulty the subtraction-thesis meets, and it cannot be sidestepped.

The thesis: "thinning" is neither a halfway house nor a degree-magnitude, but the real unit of reduction by which subtraction operates upon a kind of graded fetter. The whole resolution lies in one overlooked structural fact: the desire-realm's greed and hatred are not a single slab but divide into nine grades — top-of-top, top-of-middle, top-of-bottom, middle-of-top, middle-of-middle, middle-of-bottom, bottom-of-top, bottom-of-middle, bottom-of-bottom. Once divided into grades, "severance" can proceed grade by grade; sever some grades and leave the rest — what is severed is truly severed (the grades severed cannot re-arise), what remains is truly unsevered (to be exhausted later). "Thinning," as thinning, is not the whole vaguely grown one shade fainter, but six of the nine grades permanently severed, the lower three definitely remaining.

Thus "thinning" is not the halfway house of accumulation but the by-grade realization of subtraction. The wall is not "half-fallen" (a degree-magnitude) but "a nine-part wall whose six parts are permanently taken down" (a count of severance). What is measured is still "what is gone" (the six grades permanently severed), not "how much has faded" (the weight of experience). The paper argues accordingly: Section II presents the scriptural-commentarial basis (the scriptural definition of thinning; the nine-grade, sixth-grade mechanism of the treatises); Section III, the core argument, establishes in three layers that thinning is a unit of reduction (the graded structure makes "thinning" a countable severance; the six grades severed are a true cessation, not attenuation; the one return is the fixed number this reduction yields); Section IV omits convergence; Section V offers corrections (especially that "thinning" is not a faintness of experience); Section VI concludes.

II. The Canonical Basis

2.1 Scripture: the once-returner = three fetters severed, greed-hatred-delusion thinned

The Buddha states the once-returner's definition outright. Saṃyukta-āgama, fascicle 29 (the four-fruit definition cited in P01): 「何等為斯陀含果？謂三結斷，貪、恚、癡薄」 — "What is the fruit of the once-returner? The three fetters severed, and greed, hatred, delusion thinned."¹ Note its structure: the once-returner's definition has two parts — "the three fetters severed" (inheriting the stream-enterer's total severance) + "greed-hatred-delusion thinned" (the newly added reduction). The former part is the inheritance of total severance; the latter is what is distinctive of the once-return position. So "thinning" does not replace "severance"; on the basis of "the three fetters already wholly severed," it adds a further by-grade reduction.

The same sūtra (the Ānāpānasati-context passage) lists it in four-fruit sequence: 「三結盡，得須陀洹果；三結盡，貪、恚、癡薄，得斯陀含果；五下分結盡，得阿那含果」 — "the three fetters exhausted, one gains the stream-fruit; the three fetters exhausted and greed-hatred-delusion thinned, one gains the once-return fruit; the five lower fetters exhausted, one gains the non-return fruit."² The difference of the fruits, at the once-returner node, lies precisely in the four characters "greed-hatred-delusion thinned" — the mediating reduction between the stream-enterer (three fetters exhausted) and the non-returner (five lower exhausted).

2.2 The treatises' mechanism: nine grades of cultivation-defilement, severed through the sixth, only the lower remaining

What makes "thinning" thinning, the treatises gloss with no vagueness at all. Abhidharmakośa, fascicle 24:

即預流者進斷欲界一品修惑乃至五品，應知轉名一來果向，若斷第六成一來果，彼往天上一來人間而般涅槃名一來果，過此以後更無生故。此或名曰薄貪瞋癡，唯餘下品貪瞋癡故。³

"The stream-enterer, advancing to sever the desire-realm's cultivation-defilements from the first grade through the fifth, should be known as turning into the once-return approach; if he severs the sixth, he becomes the once-return fruit. He goes once to the heavens and once to the human world and there attains final nibbāna — called the once-return fruit, because thereafter there is no further birth. This is also named 'thinning greed-hatred-delusion,' because only the lower-grade greed-hatred-delusion remains."

The mechanism is wholly here. First, the desire-realm cultivation-defilements divide into nine grades (the Kośa's settled teaching on severance in the path of cultivation, nine grades from top-of-top to bottom-of-bottom). Second, the stream-enterer advances to sever "from the first grade through the fifth," named the once-return approach (severing in progress); "if he severs the sixth, he becomes the once-return fruit" — severed through the sixth grade, he becomes the once-returner. Third, why "thinning"? "Because only the lower-grade greed-hatred-delusion remains" — six of the nine grades severed (the upper six: top-of-top through middle-of-bottom), only the lower three (bottom-of-top, bottom-of-middle, bottom-of-bottom, i.e. the "lower grade") remaining; hence "thinning."

The exact sense of "thinning" is thereby clear: not "greed and hatred grown fainter as a whole," but "the upper six of nine grades permanently severed, only the weakest lower three remaining." To thin is to have only the lower grade remaining — a count (six of nine severed), not a quantum-feel (how many shades fainter).

⚠️ A note on register: the once-returner's definition "three fetters severed, greed-hatred-delusion thinned" (2.1) is stated outright in the Āgamas; the counting-mechanism "nine grades of cultivation-defilement, severing the sixth makes a once-returner, only the lower remaining" (2.2) is the Kośa's fine teaching on the path of cultivation — the nine-grade division being Abhidharma's structuring of "thinning," consonant with scripture's "thinning" but finer; drawn on here with its register as treatise marked.

III. The Core Argument

3.1 The graded structure makes "thinning" a countable severance, not a faintness of degree

That "thinning" can escape the charge of "degree-magnitude" hangs entirely on one premise: the desire-realm's greed and hatred are graded. If greed and hatred were a single indivisible slab, then "thinning" could indeed only be "the whole slab grown fainter" — a degree-magnitude, falling exactly under the earlier papers' rebuke. But the treatises declare them divided into nine grades; and once divisible by grade, "severance" can fall upon the discrete unit of the "grade": sever one grade, two… through the sixth. Each grade's severance is an "all-or-nothing" event (that grade severed or unsevered), not "faded by so many tenths."

So "thinning" is redefined as a count: the number of grades severed (six). It measures not "by how much the concentration of greed and hatred has dropped" (uncountable, and an experience) but "how many of the nine grades are permanently severed" (countable, and a severance). This is precisely the bone of subtraction: measuring "what is gone" (the six grades severed), not "how the remainder feels." A nine-part wall, six parts taken down, three remaining — "six parts taken down" is a count of severance, unrelated to the impression that "the wall looks fainter." The graded structure is the key by which "thinning" is admitted into subtraction rather than falling into degree-magnitude.

An ordinary analogy: a string of nine lamps, six extinguished, three remaining. You would not say "this string has dimmed by 67% overall" (degree-magnitude, impression); you would say "six of nine are out, three remain" (count, discrete). "Thinning" is the latter, not the former.

3.2 The six grades severed are a true cessation, the lower remaining a true non-severance — thinning is "partial total-severance," not "attenuation"

A layer deeper: the severance of the six grades is the same kind of severance as the stream-enterer's severance of three fetters — both an unconditioned cessation, severed and unable to re-arise (P01 §3.1). The severance of the first through sixth grade is, at each grade, a true severance: that grade's greed and hatred are permanently extinguished and do not re-arise — not "temporarily suppressed," not "faint while in meditation but thick again on emerging." Likewise the remaining lower three grades are a true non-severance — fetters still present, to be exhausted at the non-return position (severing the seventh through ninth grade).

This radically distinguishes "thinning = partial total-severance" from "thinning = attenuation of the whole." Attenuation of the whole (degree-magnitude) is: greed and hatred still wholly present, only lower in intensity — capable of growing strong again on meeting conditions out of meditation, no grade truly severed. Partial total-severance (subtraction) is: the upper six grades' greed and hatred truly extinguished and not recurring, the lower three grades wholly untouched — what is severed wholly severed, what is unsevered wholly present, the boundary sharp. Scripture's "thinning" is the latter: the six-grade wall permanently down (true severance), the three-grade wall unmoved (truly present); "thinning" depicts the fact that "the wall is short by six parts," not the impression that "the wall has grown faint."

Thus "thinning," far from violating subtraction, is precisely subtraction's subtle display: it proves the "severance" of subtraction can fall upon a unit finer than "the whole fetter" (the grade), each grade's severance still a true, non-re-arising severance. The once-returner is not "an arahant-of-the-non-returner done halfway" (a halfway house, degree) but a fixed reduction-position of "six of the nine desire-realm grades of greed-and-hatred permanently severed."

✅ Doctrinally sound: the Kośa's "severs the sixth, becomes the once-return fruit" and "because only the lower-grade greed-hatred-delusion remains" establish that "thinning" = the upper six grades truly severed, the lower grade truly present — a partial total-severance, not an attenuation of the whole. The six grades severed are a cessation (true severance, non-re-arising), of the same kind as the stream-enterer's severance; hence "thinning" wholly accords with subtraction, not degree-magnitude.

3.3 The one return is the fixed number this reduction yields: the remaining grades being finite, rebirth is fixed

The once-returner is named "one return" — one round-trip between heaven and the human world, then final nibbāna. This number "one return" is exactly the fixed rebirth-number the reduction of 3.1–3.2 yields, on the same principle as P04's seven returns (certainty as a corollary of severance, not a word of reassurance).

The mechanism: the force of desire-realm-bound rebirth hangs on the quantity of desire-realm cultivation-defilement (the nine grades of greed-hatred-delusion). The stream-enterer, with nine grades unsevered, has at most seven returns; the once-returner, having severed six and with only the lower three remaining, has his binding-force greatly reduced, so the rebirths needed reduce to "one return" — one going to the heavens, one return to the human world, where, the remaining grades ripening, he attains final nibbāna, "because thereafter there is no further birth" (2.2). The number "one" is not a bestowed count of chances but the structural quantity "the upper bound of rebirth the binding of the remaining lower grade requires to unfold" (on the same principle as P04's seven returns being the finite fixed number of a ripening continuum).

Thus the once-returner's "one return" and the stream-enterer's "at most seven returns" are two marks on one logic: the rebirth-number decreases with the number of grades severed (nine unsevered → at most seven; six severed, three remaining → one return; five lower exhausted → non-return, next paper). The more the reduction, the less the binding, the more fixed and the fewer the rebirths. "One return" is the projection of subtraction onto the rebirth-number, corresponding tightly with "thinning" (six grades severed).

Closing through the approach-fruit grammar (continuing P02): the once-return approach is the moving aspect of advancing to sever the desire-realm cultivation-defilements from the first grade through the fifth ("turns into the once-return approach," 2.2); the once-return fruit is the resting aspect of having severed the sixth, only the lower remaining (the cessation of thinning established and abiding). The fruit standing, "one return" is what that fruit's resting aspect spreads out upon rebirth.

IV. Interdisciplinary Convergence

(This paper deliberately omits the interdisciplinary-convergence section; the rationale appears in Section VI. Although "severing grade by grade" resembles the discreteness of "energy-level transition" in quantum physics — discrete rather than continuous — energy levels are a description of physical states and what transitions is conditioned, alike in face but unlike in spirit with the by-grade true severance of the nine-grade cessation; a forced convergence would misrepresent, so better omitted.)

V. Middle-Way Corrections

❌ Misreading 1: "thinning = the experience of greed and hatred grown fainter as a whole." The whole paper dismantles this. "Thinning" is not a faintness of experience (degree-magnitude, uncountable) but the count of six of nine grades permanently severed (severance, discrete). To read "thinning" as the subjective sense of "having practised until greed and hatred are somewhat lighter" is the variant of "measuring fruit by experience" the earlier papers rebutted — and it breaks on meeting conditions out of meditation (experience can regress, true severance cannot). The criterion of thinning is "how many grades severed," not "how faint it feels."

⚠️ Correction 2: the once-returner is not "an arahant-of-the-non-returner done halfway." "The once-returner lies between the stream-enterer and the non-returner" is easily read as "a halfway point in degree" — as if a midpoint on a continuous slider. In fact the once-returner is a fixed reduction-position: six of the nine desire-realm grades permanently severed, the boundary sharp, not a vague midpoint of "half-severed." His difference from the non-returner is "the lower three grades unsevered" versus "all nine severed" (a discrete difference), not "faint" versus "fainter" (a difference of degree). The halfway-house image is an error.

⚠️ Correction 3: the "lower grade" of "only the lower grade remaining" is not "slight to the point of negligible" but "a true fetter not yet severed." The remaining lower three grades, though weakest, are still truly unsevered fetters, still possessing the force of binding to the desire-realm and summoning rebirth (hence the still-required "one return"). Do not, because they are "lower grade" and "weakest," mistake them for "all but severed." Subtraction does not admit "all but" — unsevered is unsevered; the lower-grade fetters must still be truly severed at the non-return position. The once-returner's "incompleteness" is a true incompleteness (the three grades present), not "near enough."

VI. Conclusion

Essential restatement. The once-returner's "thinning greed-hatred-delusion" is no exception to subtraction but subtraction's subtle realization upon a graded fetter. The desire-realm's greed and hatred divide into nine grades; the stream-enterer advances to sever through the sixth and becomes a once-returner, "named thinning because only the lower-grade greed-hatred-delusion remains" (2.2). "Thinning" is a count (six grades permanently severed), not a quantum-feel (faintness of experience) (3.1); the six grades severed are a true cessation, the lower grade remaining a true non-severance, so thinning is "partial total-severance," not "attenuation of the whole" (3.2); the one return is the fixed rebirth-number this reduction yields, on the same principle as the seven returns (3.3). The wall is not half-fallen but a nine-part wall whose six parts are permanently taken down.

Guidance for practice. The understanding a practitioner should form of "thinning" is not the self-impression "my greed and hatred seem to have lightened" (which can err, can regress) but a faithful recognition of "by-grade true severance": the question is not "how much lighter do I feel" but "here, has even one grade of desire-realm greed-and-hatred been truly and permanently extinguished, not to recur on meeting conditions." Faintness of experience may thicken again on emerging from meditation — not a fruit; a grade's true severance does not recur on meeting conditions — that is. To one who, finding greed and hatred seemingly lighter, calls himself a once-returner, this paper is a reminder: the criterion of thinning is stricter than experience — it is the count of grades permanently severed, not the subjective sense of thick or faint.

Open questions. This paper cut Section IV because, though "severing grade by grade" formally resembles the discreteness of energy-level transition, energy levels are conditioned states, alike in face but unlike in spirit with the nine-grade cessation. A genuine question for later: is the nine-grade division of desire-realm cultivation-defilements a purely Abhidharma construction, or is there already a structural seed in the Āgama word "thinning"? This touches the interpretive history of "thinning" across scripture and treatise, beyond this paper's measuring-theme. Further, this Part (the once-returner) is here complete in a single paper. The next Part (the non-returner, from P06) will continue this by-grade subtraction to its limit: the lower three grades of desire-realm cultivation-defilement also exhausted (the seventh through ninth grade), the five lower fetters wholly severed — and there a new threshold, heavier than "thinning," will be met: not returning to the desire-realm. "Thinning" is a reduction of desire-realm binding; "the five lower exhausted" is the severance of desire-realm binding; from "one return" to "non-return" is the qualitative change of rebirth from "a fixed number" to "no return to this realm." This is what the next paper must handle.

Notes

References

I. Buddhist Primary Sources

Saṃyukta-āgama (雜阿含經). Trans. Guṇabhadra. T02, no. 0099. (Fascicle 29: the four-fruit definition; the Ānāpānasati-context four-fruit sequence.)
Abhidharmakośa-bhāṣya (阿毘達磨俱舍論). By Vasubandhu, trans. Xuanzang. T29, no. 1558. Chapter on the Noble Ones (分別賢聖品, fascicle 24).

II. Modern Scholarship

(This paper cites no modern scholarship; the argument rests entirely on Buddhist primary sources, following the open-source spirit of "return to the source." The interdisciplinary-convergence section having been cut, no corresponding modern literature appears.)

III. Index of Canonical Citations

Point	Source	CBETA id
Once-returner = three fetters severed, greed-hatred-delusion thinned (four-fruit definition)	SĀ fasc. 29	T02n0099_p0205c02
Four-fruit fetter sequence; three exhausted + thinned = once-return fruit	SĀ fasc. 29	T02n0099_p0209b09
Nine-grade cultivation-defilement; severing the sixth makes a once-returner; named thinning, only lower grade remaining	Kośa fasc. 24	T29n1558_p0124a06

Cross-Reference Index

SRAMANA-P01, "Measuring Fruit by Subtraction," §3.1: this paper's §3.2 "the six grades severed are a true cessation" directly inherits P01's cessation (the substance of the fruit); thinning = partial total-severance, wholly according with measuring fruit by severance.
SRAMANA-P02, "The Hinge of Approach and Fruit," §3.3: this paper's §3.3 closes through the approach-fruit grammar (once-return approach = severing grades one through five; once-return fruit = the sixth grade severed).
SRAMANA-P04, "Irreversibility and the Seven Returns," §3.2: this paper's §3.3 "one return" is on the same principle as P04's "at most seven returns" — the fixed rebirth-number decreases with the number of grades severed.
SRAMANA-P06, "The Five Lower Fetters Exhausted: The Threshold of the Desire-Realm" (forthcoming): this paper's §VI foreshadows — the lower three grades also exhausted, the five lower fetters wholly severed, from "thinning" (a reduction of desire-realm binding) to "severance" (the qualitative change of desire-realm binding, no return to the desire-realm).

Paper: SRAMANA-P05 · 薄之為斷 · The Four Śrāmaṇya-phalas · Part 3 · Sakadāgāmin Author: 釋慧鏡 (Shi Huijing) · Project: 指月 / Pointing-at-the-Moon · Series: The Realization Paths（行階位歷程） License: CC BY-NC-SA 4.0 CBETA collation: 全文引用均依 CBETA 電子佛典核校（《雜阿含經》T0099、《阿毘達磨俱舍論》T1558）。Pāli 引文採 PTS reference 雙軌標示（vault 未收者俟後補）。 Repository: https://github.com/pointing-at-the-moon/realization-paths

Footnotes

Saṃyukta-āgama, fascicle 29, T02n0099_p0205c02. From the four-fruit definition: "What is the fruit of the once-returner? The three fetters severed, and greed, hatred, delusion thinned." Collated against the CBETA digital canon. ↩
Saṃyukta-āgama, fascicle 29 (Ānāpānasati context), T02n0099_p0209b09. The four-fruit fetter sequence; "the three fetters exhausted and greed-hatred-delusion thinned, one gains the once-return fruit." ↩
Abhidharmakośa-bhāṣya, fascicle 24 (Chapter on the Noble Ones, part 3), T29n1558_p0124a06. The nine-grade mechanism of the once-return approach and fruit: "advancing to sever the desire-realm's cultivation-defilements from the first grade through the fifth… if he severs the sixth, he becomes the once-return fruit… this is also named 'thinning greed-hatred-delusion,' because only the lower-grade greed-hatred-delusion remains." By Vasubandhu, trans. Xuanzang. ↩